Principled volume shader's weird behavior in Eevee
Okay this seems like a bug but only with some types of hardware. I updated Blender to 2.83.5 which was released yesterday and am so happy that they fixed it. However, it only works with newly created files. Old files still have the problem sadly.
Edit: I don't know if they really fixed it or not but I tested again and sometimes it worked sometimes it didn't.